Psychrometrically controeled jur



Jan. 4, 1944. c ow 2,338,382

PSYCHROMETRICALLY CONTROLLED AIR CONDITIONING SYSTEM Filed June 23, 1942Conan/ch50 SPACE UOLVHDdVAJ g g FREON Cbrvamss FROM SuMP gfimeqs C'-Mar/OW a ywal am ui'ibwney Patented Jan. 4, 1944 UNITED STATES PATENTole-Flor.

1 P SYOHROMETRICALLY OONTRDLLEDJAIR CONDITIONING' SYSTEM James C.Marlow, Atlanta, Ga., ass norf'toiB. F. Sturtevant Company, Boston;Mass.

Application :June 23, 1942,:SeriahllmaMByllM 9 Claims.

This invention relates to'the conditioning of 'air and relates moreparticularly torair conditioning systems and to automatic controlstherefor for maintaining desired relative humidities :and

"drybulb temperatures in the :conditionejd;space. 7'

In the processing of many materials in manufacturing, it is important tomaintain agsubstantially constant relative humidity and ;a substantiallyconstant dry bulb temperaturein-the conditioned space at anypredetermined setting of the control instruments. In so far as ,is knownin all prior. systems while it was possible to maintain'the. relativehumidity and dry -.bulb temperature within limits which had tombeaccepted as tolerant, .the fluctuations were substantial and undesired.

Objects .of 'this invention are .tomaintain .a substantially constantrelative humidity ,fllldfi substantially constant dry bulb temperaturein the" air in an air conditioned; space.

--The invention will now be described with reference .to the drawingwhich illustrates di grammatically an .air 2 conditioning system:embodying this invention.

The centrifugal fan 5 .driven;by:the;e-lectric motor 6 draws in freshoutdoor air through the inlet 1. The fresh air passesinthe order; named,through the preheater 8, betweenthe dampers 9,.vthrough the plenum;chamber l0,,the;fi;1ters II, the sprays from .thelair washerrnozzles12-,

between the finnedtubes/of the evaporator l3, through thereheater I4,between the face dampers l5 when they are open, into the plenum chamberI6; and then into the inlet of; the ian,5. The conditioned air isdischargedthrough 1,,the duct ll into the conditionedspacew.

Air recirculatedv from the space 18 isj-dra-wn by the suction of the fan5 through the, dl 9t l 9, and when the by-pass dampers, 20 inthe by passduct 2| are open, a portionof the, recirculated air passes as by-passair into the plenumchamber l6 for mixture, with the, chilled,,dehumi dified air from the evaporator I3.

-Another portion of therecirculated air from the duct I9 is drawn'intothe plenum chamber Ill and passes with the recirculated air through theabovedescribed apparatus located, between the plenum chamber H1 and thespace l8. v

As is well known the byrpass air.serves to-revheat the chilled air fortempering purposes,-and asaving in refrigerationis affectedby recircmlating air from the space served, throughgthe conditioner since thecondition of the ,recirculated air is usually nearer the .desiredconditign than the outdoor air.

ITheIGVaPOmtOI ;I may be of wellyknowmcom struction :consisting :of 1acpluralitygof :nelatively closely]spaceds'horizontal-ztubesPIQW-dQdlWlth-ZQX- tended zsurface fins, with interconnected returnbends ;and.; inlet and ioutlet :headets. zenitable fivolatile:refri'gerant zlsllch :Las '-Ereon :is supplied dram :theccompressorecondenser 2 .through-i-thexpipe #23:and-iis;returnedgthmu hlt h suction pipe :241and the: suction .-va1v e:.-';25.

steamifrom .Lthe;sourcerflfigis supplied :throu hthe rpipecfllxand (thevalve? :to; the rzpr heat rc andithroughtthetpipe 52,9 rand waivevto,the;-re-

heater [4, r s I lTne 'pulnp' 31; recirculates sprayewaterifromathe sumpF tnot illustrated) :uncierwthespray :noz zles and evap.0ra.tor n3,rthrough 13118 valve 3 ahepipei39 and;theynozzlessl2. Thewwate fllom Qnozzles :12 vpreterably sprays;upon theaeyaporator, isusualaarfloatfcontrolledgmakerup1mm? supply may-be used.

The @dry bulbethermostat 3 I and the; hy ostat 132 control -the -,oera.tion of.1.t systemnthr u h compressed .air r'from; :the, source313,.sup31ied3to these control instruments .through... the r ne 53. 4,.The dash-dot 1 lines z-indioaterair tubesl connecting the controlinstruments and the .diaphragni type motors controlledcbycthem.

'Ihe motor :3 5: is actuated byi :the,hygrostat-32 to adjust the steamvalve :.2-8=,-1-Wh ich closed. The motor 35 is biased -to ope'rate toopen the valve-=28 at an air. pressurebetween ten and=fourteen-poundsfThe motorditi is actuated by the thermostat fl to adjust the-steamvalvefmwh-ich is normally closed. The motor -38 is biasedto operate to openthe valve 30- ;at-an air pressure b'etween nine andthirteen pounds.

an leieh -.pcuud 1'. 11 6 a virqmlthe be describ -a -P en r l1 rh e qs 1ieatliesu iew y r g 32 .to the motor ,fifi passes through the val wh h iermal r-t pnen- ;,It.is.eetrel d P di pnra mi yee moto i lmwbi nintrolledfbyethe thermostat, 3 l whichact ei ti ai lel ea ditioned spacehas dropped to its predetermined temperature.

The motor 43 is actuated by the thermostat 3| to adjust the by-passdampers 20 which are normally closed. The motor 43 is biased to open thedampers 20 at an air pressure between four and nine pounds.

The motor 44 is actuated by the thermostat 3| to adjust theface dampersl5 which are normally open. The motor 44 is biased to close the dampersl5 at an air pressure between four and nine pounds.

The solenoid 45 is connected to the electric circuit of the motor 6 sothat when the switch 46 is opened for disconnecting the motor 6 from theelectric source 41, the solenoid 45 is deenergized and closes the valve48 in the air tube 34 connecting the air source 33 with the controlinstruments. This causes the motor 49 to close the normally open freshair dampers 8.

The hygrostat 32 is of the reverse acting type designed to pass air tothe motors it controls .on a falling relative humidity, If the relativehumidity in the conditioned space I8 starts to fall below the desiredcondition which, for example,

may be 65%, the hygrostat will start gradually to pass air to thevarious motors it actuates.

When the air pressure released by the hygrostat reaches four pounds, therefrigerant suction valve 25 Will be gradually closed by the motor 50and when the air pressure reaches eight pounds, the valve 25 will befully closed thus, completely shutting off the refrigeration. If this isnot sufficient to raise the relative humidityin the space IS, thehygrostat will continue to pass air fand .at seven pounds pressure thespray control valve 38 will begin to be opened by the motor 4|! and whenthe air pressure reaches eleven pounds the sprays will be full ontending to in! crease the relative humidity of the air. If in -spite ofthis, the desired relative humidity is not restored, the air pressurewill continue to build up and at ten pounds pressure, the preheatersteam valve 28 will start to be opened by the motor 35 and when the air:pressure reaches fourteen pounds, the valve 28Qwillwbe -fully open. Thiscauses maximum heatthrough jlthe preheater which results in an increaseinthe {dew point. temperature of the air leaving the ,spray from thenozzles l2. 7

Instead of using the air preheater 8 as described for raising therelative humidity of the air, a water heater supplied with steam fromthe source 26 couldbe used for heating the water supplied to the spraynozzles I2.

Instead of having the valve 25 completely closed as described, itmay bedesirable to have the valve stop adjusted so that the valve may ,bealmost but not completely closed. This will prevent the usual lowpressure control fromshuttine down the compressor, if a local,individual compressor is used, and will result in the compressor beingin condition for immediate action when the hygrostat or thermostatcalls'fo'r refrigeration. I I

It is to be noted that the operating pressures for the various motorshave been overlapped so that each proportioning motor will be inimmediate reserve and ready to perform without delay upon demand fromthe hygrostat.

" The dry'b'ulb thermostat 3| is also of the re verse acting typedesigned to pass air to the motors it controls, upon a fallingtemperature. When the dry bulb temperature in the conditioned space 18-starts-to fall below the'control temperature which, for example, may be70 F., the thermostat will start to pass air and when the air pressurehas reached four pounds, the face dampers l5 will start to be closed bythe motor 44 and the bypass dampers 20 will start to be opened by themotor 43, When the air pressure has reached nine pounds the face dampersl5 will be fully closed. If this does not raise the dry bulbtemperature, the thermostat will continue to pass air and when the airpressure reaches nine pounds, the reheater steam valve 30 will start tobe opened by the motor 33 and when the air pressure reaches thirteenpounds, the valve 30 will be fully open.

The valve 4| in the air line from the hygrostat 32 to the motor 50controlling the refrigerant suction valve 25, is controlled by thethermostat 3| so that the valve 4| is closed preventing the hygrostatfrom supplying air to close the suction valve 25 when the temperature inthe space I8 is above its predetermined setting. When this conditionoccurs and the relative humidity is too low, the operation of thepreheater and the sprays as describedhas been found sufiicient torestore the relative humidity to its predetermined point. a

In a typical installation embodying this invention the dry bulbtemperatures and the relative humidities in the conditioned space wererecorded on a standard clock driven recording chart and the fluctuationsinv the lines drawn were barely preceptible to the eye showing that thedesired conditions were maintained substantially constant for allpractical purposes.

While the controls have been illustrated and described as being of theair actuated type, electric or other equivalent controls could, ofcourse, be used. 7

While one embodiment of the invention has been disclosed for the purposeof illustration, it should be understood that the invention is notlimited to the exact apparatus and arrangement of apparatus illustrated,as modifications thereof may be suggested by those skilled in the artwithout departure from the essence of the invention.

What is claimed is:

1. An air conditioning system comprising an air heater, an air washer,an air cooling refrigerant evaporator, and including .means for movingair to be conditioned through said heater, said washer and saidevaporator and for supplying it into the space to be conditioned, aheating fluid source connected to said heater, a water source connectedto said washer, a refrigerant source connected to said evaporator, andmeans including means responsive to changes in the relative humidity insaid space for first decreasing the supply of refrigerant from saidrefrigerant source to said evaporator, for next initiating the supply ofwater from said water source to said washer, and for next initiating thesupply of fluid from said heating source to said heater, upon a fall inrelative humidity in said space below the desired level.

2. An air conditioning system comprising an air heater, an air washer,an air cooling refrigerant evaporator, and including means for movingair to be conditioned through said heater. said washer and saidevaporator and for supplying it into the space to be conditioned, aheating fluid source connected to said heater, a water source connectedto said washer, a refrigerant source connected to said evaporator, andmeans including means responsive to changes-in the viii Ha. tau-Ll)..n,-. lr rinsin relative humidity in said-space for: first decreasringithe supply of refrigerant from said refrigaerant source tosaidevaporator from a maximum to a minimum upona fall in-the' relativehumidity "itch-maximum, andsvthen if-the relative humidity ris-"notrestored, for initiating the supply of fluid .from said heating'source-and regulating it from a minimum to a maximum.

' 3: An airconditioning 'systemwomprisingr an air heater, I an airwasher, an air cooling refrig- Ferant evaporator and including means formovdag air 'to' be" conditioned-through said heater, rsaid washer "and-said evaporator and forsup- :plyingit into the space to be conditioneda-heatsource--connected--to said washer, a refrigerant source connectedto said-evaporator, and 'means including means responsive to changes in-the relative-humidity in said spacefor first decreasing'fiuidsource-connected to said heater,a Water :ing the a supply of refrigerantfrom-said refrig- 11' '1; erant source to said evaporator-froma maximumrto a minimum upon afallin the relative humidity in said space-below thedesired level, for then if the relative humidity is not restored,-initiating the supply of waterfrom said-water source to ti said washerand regulating it froma minimum to a maXimum,-and-tiren-=if the relativehumidity is not-restored, for-initiating the supply of fluid from saidheating source and regulating it from a minimum to a maximum, theregulation of said evaporator, said washer and said heater beingoverlapped whereby the supply of water to said washer is initiatedbefore the supply of refrigerant to said evaporator has been reduced toa minimum, and the supply of heating fluid to said heater beinginitiated before the supply of water to said washer has been increasedto a maximum.

4. An air conditioning system comprising an air cooling refrigerantevaporator, an air heater on the downstream side of said evaporator,face dampers for bypassing air from said evaporator around said heater,a duct conducting air from the conditioned space as bypass air to thedownstream side of said heater, a duct damper in said duct, said systemincluding means for moving air through said evaporator and heater andfor supplying it into the space to be conditioned and for moving airfrom said space through said duct, and means including a thermostatresponsive to temperature changes in said space for first decreasing thesupply of refrigerant to said evaporator, for next adjusting said facedampers towards closed position and adjusting said duct damper towardsopen position, and for next admitting a heating medium into said heaterupon a fall in the temperature in said space below the desired level.

5. An air conditioning system comprising an air cooling refrigerantevaporator, an air heater on the downstream side of said evaporator,face dampers for bypassing air from said evaporator around said heater,a duct conducting air from the conditioned space as bypass air to thedownstream side of said heater, a duct damper in said duct, said systemincluding means for moving air through said evaporator and heater andfor supplying it into the space to be conditioned, and for moving airfrom said space through said duct, and means including a thermostatrespon ir iii-temp rat e, a e in. d .0.r: fir t ad u n t e sup l qfe i isr Said nora ru a ll. '1 atem ere ,in; said space ,below, the desiredleveL from a maximum to a minimum, then if thetempe gisinot restored,for adjusting said face dam W rom-a maximum open to a minimum. open-psistionandi for adjusting sai d ct damper ta mi im m; openv t m m -mpgn-P9$ Q9. ,and; then if,the,temperature is not-restored fw initiatingthe supply of, heating fluid to, said heater-andadjusting same from aminimumjto ,a; maximum ,until the temperature is. restored. ;-6, An airtconditioning system comprising (an air :cooling refrigerant evaporator,an air. he tier mngtheidow s am side of ai e a ora es, ,ldam-persdo-rbypassing; air from said evaporator tarollnd. ,said heater, a ductconducting, air, froth "the; conditioned ,spaceas bypass air tothedovvn- -stream side of said heater, a ductdamper in said duct, said,system includingmeans for, moving air-through said evaporator andheater, and ,for supplying it into the space to beconditio andfor movingair from saidspace througnsa d duct, 1 and means including a thermostat1j.espon- =sive to temperaturephangesin said pace ,first adjustingthesupply, of refri eilahttos' d ievaporatorupon a fall in the temperaturen said space below the desired level, fr orn a maxfrom a maximum open toa minimum, open p9- sition and for adjusting said duct damper from aminimum open to a maximum open position, and then if the temperature isnot restored, for initiating the supply of heating fluid to said heaterand adjusting same from a minimum to a maximum until the temperature isrestored, the adjustments of said supply refrigerant, of said dampersand of said supply of heating fluid being overlapped whereby theadjustments of the dampers are started before the supply of refrigeranthas been reduced to a minimum, and the supply of the heating fluid isinitiated before the face dampers have reached their minimum openposition and the duct damper has reached its maximum open position.

7. An air conditioning system comprising a humidifier, an air cooler, anair heater at the downstream side of said cooler, face dampers forbypassing air from said cooler around said heater, a duct for conductingair from the conditioned space as bypass air to the downstream side ofsaid heater, a damper in said duct, said system including means formoving air through said humidifier, cooler and heater and supplying itinto said space and for moving air from said space through said duct,means including means responsive to changes in the relative humidity insaid space for first decreasing the effectiveness of said cooler, upon afall in the relative humidity in said space, from a maximum to aminimum, and then if the relative humidity is not restored, initiatingthe action of said humidifier and then increasing its eifectiveness froma minimum to a maximum, and means including a thermostat responsive totemperature changes in said space for first adjusting the supply ofcooling medium to said cooler upon a fall in the temperature in saidspace below the desired level, from a maximum to a minimum, and then ifthe temperature is not restored for adjusting said damper from minimumopen position to maximum open position and for adjusting said facedampers from maximum open position to minimum open position, and

then if the temperature is not restored foractu- ='ating said heater andfor increasing its effective- "'-ness from a minimum to a maximum.

8. An air conditioning system comprising a humidifier, an air coolingrefrigerant evaporator, I

an air heater at the downstream side of said means for moving airthrough said humidifier, evaporator and heater and supplying it intosaid space and for moving air from said space through said duct, meansincluding means re- "sponsive to changes in the relative humidity insaid space for first adjusting the supply of refrigerant to saidevaporator, upon a fall in the relative humidity in said space, from amaximum to a minimum, and then if the relative humidity is not restored,initiating the action of said humidifier and then increasing itseffectiveness from a minimum to a maximum, means including a thermostatresponsive to temperature changes in said space for first adjusting thesupply of refrigerant to said evaporator upon a fall in the temperaturein said space below the desired level, from a maximum to a -minimum, andthen if the temperature isnot restored for adjusting said damper from aminimum open position to maximum open position and for adjusting saidface dampers from maximum open position to minimum open position,

and then if the temperature is not restored for actuating said heaterand forincreasing its effectiveness from a minimum to a maximum,

and means controlled by said thermostat for preventing said humidityresponsive means from decreasing the supply of refrigerant to saidevaporator when the temperature in said space is above the desiredlevel. I I

9; An air, conditioning system comprising a humidifier, an air cooler,air reheating means, said system including means for moving air throughsaid humidifier, said cooler and said reheating means and for supplyingit into the conditioned space, means including means responsive tochanges in the relative humidity in said space for first adjusting theefiectiveness of said cooler towards minimum upon a decrease in therelative humidity in said space below the desired level and then if thehumidity is not restored, for actuating said humidifier, means includinga thermostat responsive to temperature changes in said space for firstadjusting the effectiveness of said cooler towards minimum, upon a fallin the temperature in said space below the desired level, and then ifthe temperature is not restored, for initiating the action of saidreheating means, and means controlled by said thermostat for preventingsaid humidity responsive means from decreasing the effectiveness of saidcooler when the temperature in said space is above the desired level.

JAMES C. MARLOW.

